Hybrid-electric and pure electric vehicles rely on a traction battery to provide power for propulsion. To ensure optimal operation of the vehicle, various properties of the traction battery may be monitored. One useful property is the battery power capability which indicates how much power the battery may supply or absorb at a given time. Another useful property is the battery state of charge which indicates the amount of charge stored in the battery. The battery properties are important for controlling operation of the battery during charging/discharging, maintaining the battery within safe operating limits, and balancing cells of the battery.
Battery properties may be measured directly or indirectly. Battery voltages and currents may be measured directly using sensors. Other battery properties may require that one or more parameters of the battery be estimated first. The estimated parameters may include resistances, capacitances, and voltages associated with the traction battery. The battery properties may then be calculated from the estimated battery parameters. Many prior art schemes are available for estimating the battery parameters, including implementing a Kalman filter model to recursively estimate the model parameters.